This invention concerns air gap arrangements and more particularly antisiphon type air gap arrangements for the water supply inlet to dishwasher appliances. Most communities require vacuum breaking antisiphon devices to be incorporated in plumbing installations in the inlet to an appliance or other installation, if the supply tube supply line may become submerged in potentially contaminated water. This is since the water supply system may occasionally develop a negative pressure at the supply inlet, causing the contaminated water to be drawn into the water system of the community and endangering the health of those using the water supply.
One vacuum breaking or antisiphon arrangement which has been employed in the past in home appliances has been the provision of an air gap interposed in the supply system for the appliance. In the case of a dishwasher, such an air gap is typically provided by the supply tube communicating with the tub which is mounted exteriorly of the machine cabinet and provided with a funnel into which the fill water is directed under the control of the dishwasher fill valve. This arrangement is relatively complex and costly since long lengths of tubing may be required and the exterior mounting requires separate bracketry. This also creates potential leak points at the hose connections and the points where the supply tube passes into the tub bottom, as well as at the point of entry of any fasteners which must be employed.
The exterior mounting of the air gap arrangement is intended to prevent the possible induction of contaminated overspray in the machine interior, as well as to locate the air gap above "flood" level in the machine. That is, the maximum level reached in the machine after failure of all of the level controls designed into the machine.
Most dishwashers are protected by "failsafe" means whereby malfunction of the fill valve or other failures in the system do not result in overfilling of the machine and possible flooding thereof. However, the effectiveness of the antisiphon means is usually tested with such failsafe means defeated, allowing the machine to flood to whatever maximum level is reached in the machine with the safety arrangements defeated.
Accordingly, it is desirable that the air gap is located well above any potential flood level in the machine and exteriorly of the cabinet to insure that clean exterior air is drawn into the air gap when suction is applied to the supply line.
Accordingly, it is an object of the present invention to provide an air gap arrangement particularly adapted to dishwashers which eliminates the cost and potential maintenance problems of the conventional air gap arrangement described above.
It is a further object of the present invention to provide such air gap arrangements which insure the presence of an air gap between the fill tube and the water disposed in the machine under flood conditions.
It is still a further object of the present invention to provide such an air gap arrangement which prevents the possible induction of contaminated overspray from the machine interior into the supply line under suction conditions.